Gamma-ray Burst 210807A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:20:06 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  GRB_RA:           76.677d {+05h 06m 43s} (J2000),
                    77.143d {+05h 08m 34s} (current),
                    75.601d {+05h 02m 24s} (1950)
  GRB_DEC:         +58.245d {+58d 14' 43"} (J2000),
                   +58.272d {+58d 16' 21"} (current),
                   +58.178d {+58d 10' 43"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       0 [cnts]    Image_Peak=2270 [image_cnts]
  TRIGGER_DUR:     112.000 [sec] 
  TRIGGER_INDEX:   20000     E_range: 15-50 keV
  BKG_INTEN:       0 [cnts]
  BKG_TIME:        0.00 SOD {00:00:00.00} UT
  BKG_DUR:         0 [sec]
  GRB_DATE:        19433 TJD;   219 DOY;   21/08/07
  GRB_TIME:        36220.49 SOD {10:03:40.49} UT
  GRB_PHI:           3.83 [deg]
  GRB_THETA:        49.34 [deg]
  SOLN_STATUS:     0x20000013
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    12.28 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +7  +1  +2  +0  +0 -48  +0 
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 31"}
  SUN_DIST:         60.83 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.76d {+08h 19m 03s}  +23.67d {+23d 40' 08"}
  MOON_DIST:        48.23 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.63, 10.43 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       81.47, 35.20 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger 
  integration interval;  
  COMMENTS:        probably due to it occurring during a Malindi downlink session.  
  COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are
   undefined.)  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 17.54,15.32 [deg].  
  COMMENTS:           
  COMMENTS:        NOTE: This BAT event is temporally(59.0<100sec) coincident with the INTE
  GRAL_SPIACS event (trignum=9333).  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:          GCN/INTEGRAL NOTICE
  NOTICE_DATE:    Sat 07 Aug 21 10:06:00 UT
  NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
  TRIGGER_NUM:    9333,   Sub_Num: 0
  GRB_INTEN:      9.10 [sigma]
  GRB_TIME:       36279.73 SOD {10:04:39.73} UT
  GRB_DATE:       19433 TJD;   219 DOY;   21/08/07
  COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.  
  COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000.  
  COMMENTS:       The SPIACS lightcurve can be found at:  
  COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2021-08/2021-08-07T10-04-39.5580-11513-48016-0.lc
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:20:39 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  GRB_RA:           76.6815d {+05h 06m 43.55s} (J2000),
                    77.1476d {+05h 08m 35.42s} (current),
                    75.6047d {+05h 02m 25.13s} (1950)
  GRB_DEC:         +58.2503d {+58d 15' 01.0"} (J2000),
                   +58.2775d {+58d 16' 39.0"} (current),
                   +58.1836d {+58d 11' 01.0"} (1950)
  GRB_ERROR:       4.9 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       4.08e-09 [erg/cm2/sec]
  GRB_SIGNIF:      11.09 [sigma]
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36422.39 SOD {10:07:02.39} UT,   201.9 [sec] since BAT Trigger Time
  TAM[0-3]:        327.67 237.17 261.65 243.21
  AMPLIFIER:       2
  WAVEFORM:        134
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 30"}
  SUN_DIST:         60.83 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.77d {+08h 19m 04s}  +23.67d {+23d 40' 05"}
  MOON_DIST:        48.23 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.63, 10.44 [deg] galactic lon,lat of the burst
  ECL_COORDS:       81.47, 35.20 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Coordinates.  
  COMMENTS:        The XRT position is 0.34 arcmin from the BAT position.
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:20:49 UT
  NOTICE_TYPE:     Swift-XRT Image
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  GRB_RA:           76.6815d {+05h 06m 43.5s} (J2000),
                    77.1476d {+05h 08m 35.4s} (current),
                    75.6047d {+05h 02m 25.1s} (1950)
  GRB_DEC:         +58.2503d {+58d 15' 01.0"} (J2000),
                   +58.2775d {+58d 16' 39.0"} (current),
                   +58.1836d {+58d 11' 01.0"} (1950)
  GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
  GRB_INTEN:       123 [cnts]
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36422.39 SOD {10:07:02.39} UT,   201.9 [sec] since BAT Trigger Time
  CENTROID_X:      350.66,  raw= 351  [pixels]
  CENTROID_Y:      333.68,  raw= 334  [pixels]
  ROLL:            106.58 [deg]
  GAIN:            1
  MODE:            3, Long Image mode
  WAVEFORM:        134
  EXPO_TIME:       2.50 [sec]
  GRB_POS_XRT_Y:   83.87
  GRB_POS_XRT_Z:   101.99
  IMAGE_URL:       sw01064221000msxps_rw.img
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 30"}
  SUN_DIST:         60.83 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.77d {+08h 19m 04s}  +23.67d {+23d 40' 04"}
  MOON_DIST:        48.24 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.63, 10.44 [deg] galactic lon,lat of the burst
  ECL_COORDS:       81.47, 35.20 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Image.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:20:52 UT
  NOTICE_TYPE:     Swift-XRT Processed Image
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  GRB_RA:           76.6815d {+05h 06m 43.5s} (J2000),
                    77.1476d {+05h 08m 35.4s} (current),
                    75.6047d {+05h 02m 25.1s} (1950)
  GRB_DEC:         +58.2503d {+58d 15' 01.0"} (J2000),
                   +58.2775d {+58d 16' 39.0"} (current),
                   +58.1836d {+58d 11' 01.0"} (1950)
  GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
  GRB_INTEN:       123 [cnts]
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36422.39 SOD {10:07:02.39} UT,   201.9 [sec] since BAT Trigger Time
  CENTROID_X:      350.66,  raw= 351  [pixels]
  CENTROID_Y:      333.68,  raw= 334  [pixels]
  ROLL:            106.58 [deg]
  GAIN:            1
  MODE:            3, Long Image mode
  WAVEFORM:        134
  EXPO_TIME:       2.50 [sec]
  GRB_POS_XRT_Y:   83.87
  GRB_POS_XRT_Z:   101.99
  IMAGE_URL:       sw01064221000msxps_rw.img
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 30"}
  SUN_DIST:         60.83 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.77d {+08h 19m 04s}  +23.67d {+23d 40' 04"}
  MOON_DIST:        48.24 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.63, 10.44 [deg] galactic lon,lat of the burst
  ECL_COORDS:       81.47, 35.20 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Processed Image.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:21:07 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  GRB_RA:           76.677d {+05h 06m 43s} (J2000),
                    77.143d {+05h 08m 34s} (current),
                    75.601d {+05h 02m 24s} (1950)
  GRB_DEC:         +58.245d {+58d 14' 43"} (J2000),
                   +58.272d {+58d 16' 21"} (current),
                   +58.178d {+58d 10' 43"} (1950)
  GRB_DATE:        19433 TJD;   219 DOY;   21/08/07
  GRB_TIME:        36220.49 SOD {10:03:40.49} UT
  TRIGGER_INDEX:   20000
  GRB_PHI:           3.83 [deg]
  GRB_THETA:        49.34 [deg]
  DELTA_TIME:      0.00 [sec]
  TRIGGER_DUR:     112.000 [sec] 
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    12.28 [sigma]
  LC_URL:          sw01064221000msb.lc
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 30"}
  SUN_DIST:         60.83 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.77d {+08h 19m 05s}  +23.67d {+23d 40' 02"}
  MOON_DIST:        48.24 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.63, 10.43 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       81.47, 35.20 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:           
  COMMENTS:        The next comments were copied from the BAT_POS Notice:  
  COMMENTS:        This is an image trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 17.54,15.32 [deg].  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:21:28 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  POINT_RA:         76.721d {+05h 06m 53s} (J2000)
  POINT_DEC:       +58.219d {+58d 13' 09"} (J2000)
  POINT_ROLL:      106.583d
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36430.61 SOD {10:07:10.61} UT,   210.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        6.375
  N_STARS:         80
  X_OFFSET:        232 [pixels]
  Y_OFFSET:        552 [pixels]
  X_MAX:           1191 [pixels]
  Y_MAX:           1511 [pixels]
  DET_THRESH:      22
  PHOTO_THRESH:    13
  SL_URL:          sw01064221000msufc0210.fits
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 30"}
  SUN_DIST:         60.80 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.77d {+08h 19m 06s}  +23.67d {+23d 40' 00"}
  MOON_DIST:        48.21 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.67, 10.43 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       81.49, 35.17 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:21:47 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  POINT_RA:         76.721d {+05h 06m 53s} (J2000)
  POINT_DEC:       +58.219d {+58d 13' 09"} (J2000)
  POINT_ROLL:      106.583d
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36430.61 SOD {10:07:10.61} UT,   210.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        6.375
  N_STARS:         80
  X_OFFSET:        232 [pixels]
  Y_OFFSET:        552 [pixels]
  X_MAX:           1191 [pixels]
  Y_MAX:           1511 [pixels]
  DET_THRESH:      22
  PHOTO_THRESH:    13
  SL_URL:          sw01064221000msufc0210.fits
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 29"}
  SUN_DIST:         60.80 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.78d {+08h 19m 06s}  +23.67d {+23d 39' 59"}
  MOON_DIST:        48.21 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.67, 10.43 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       81.49, 35.17 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Source List.  
  COMMENTS:        All 4 attachments are included.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:23:43 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  POINT_RA:         76.721d {+05h 06m 53s} (J2000)
  POINT_DEC:       +58.219d {+58d 13' 09"} (J2000)
  ROLL:            106.583d
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36430.61 SOD {10:07:10.61} UT,   210.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     650023658
  X_OFFSET:        536 [pixels]
  Y_OFFSET:        842 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       696
  Y_GRB_POS:       1002
  BINNING_INDEX:   1
  IM_URL:          sw01064221000msuni0238.fits
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 28"}
  SUN_DIST:         60.80 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.80d {+08h 19m 11s}  +23.66d {+23d 39' 48"}
  MOON_DIST:        48.22 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.67, 10.43 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       81.49, 35.17 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Image.  
  COMMENTS:        The GRB Position came from the XRT Position Command.  
  COMMENTS:        The image has 2x2 binning (compression).  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:23:58 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  POINT_RA:         76.721d {+05h 06m 53s} (J2000)
  POINT_DEC:       +58.219d {+58d 13' 09"} (J2000)
  ROLL:            106.583d
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36430.61 SOD {10:07:10.61} UT,   210.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     650023658
  X_OFFSET:        536 [pixels]
  Y_OFFSET:        842 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       696
  Y_GRB_POS:       1002
  BINNING_INDEX:   1
  IM_URL:          sw01064221000msuni0238.fits
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 28"}
  SUN_DIST:         60.80 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.80d {+08h 19m 11s}  +23.66d {+23d 39' 46"}
  MOON_DIST:        48.22 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.67, 10.43 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       81.49, 35.17 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Image.  
  COMMENTS:        The GRB Position came from the XRT Position Command.  
  COMMENTS:        The image has 2x2 binning (compression).  
  COMMENTS:        All 4 attachments are included.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Aug 21 10:24:43 UT
  NOTICE_TYPE:     Swift-UVOT Position
  TRIGGER_NUM:     1064221,   Seg_Num: 0
  GRB_RA:           76.6829d {+05h 06m 43.89s} (J2000),
                    77.1490d {+05h 08m 35.76s} (current),
                    75.6061d {+05h 02m 25.47s} (1950)
  GRB_DEC:         +58.2497d {+58d 14' 58.9"} (J2000),
                   +58.2769d {+58d 16' 36.9"} (current),
                   +58.1830d {+58d 10' 58.8"} (1950)
  GRB_ERROR:       0.6 [arcsec radius, statistical only]
  GRB_MAG:         17.00 +/- 0.14 [mag]
  FILTER:          10, White
  IMG_START_DATE:  19433 TJD;   219 DOY;   21/08/07
  IMG_START_TIME:  36427.00 SOD {10:07:07.00} UT,   206.5 [sec] since BAT Trigger Time
  SUN_POSTN:       137.61d {+09h 10m 26s}  +16.29d {+16d 17' 27"}
  SUN_DIST:         60.83 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
  MOON_POSTN:      124.80d {+08h 19m 13s}  +23.66d {+23d 39' 42"}
  MOON_DIST:        48.26 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:      151.63, 10.44 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       81.47, 35.20 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT UVOT Position Notice.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The UVOT position is 3.2 arcsec from the XRT position.  
  COMMENTS:        Result based on Genie data.  
  COMMENTS:        Notice generated automatically.  
  

• GCN Circular #30600
  A. Y. Lien (GSFC/UMBC), C. Gronwall (PSU), J.D. Gropp (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 10:03:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210807A (trigger=1064221). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 76.677, +58.245 which is

     RA(J2000) = 05h 06m 43s
     Dec(J2000) = +58d 14' 43"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Because this is an image trigger, the actual light curve structure requires further ground data analysis. The 112-s image trigger indicates that this is a long burst.
  The XRT began observing the field at 10:07:02.3 UT, 201.9 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 76.6815, 58.2503 which is equivalent to:

     RA(J2000)  = 05h 06m 43.56s
     Dec(J2000) = +58d 15' 01.1"
  

  with an uncertainty of 11.1 arcseconds (radius, 90% containment). This location is 20 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
  The initial flux in the 2.5 s image was 4.08e-09 erg cm^-2 s^-1 (0.2-10 keV).
  UVOT took a finding chart exposure of 150 seconds with the White filter starting 210 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at

    RA(J2000)  =	05:06:43.90 =  76.68293
    DEC(J2000) = +58:14:59.2  =  58.24978
  

  with a 90%-confidence error radius of about 0.61 arc sec. This position is 3.3 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.00 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.409.
  Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
• GCN Circular #30602
  Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia and A. J. Castro-Tirado, M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:
  The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 16 min to the Swift trigger of GRB 210807A (Lien et al., GCNC 30600). The first image (1s exposure, clear-filter) was obtained at 10:20:19.5 UT. We detected the optical afterglow at the position reported by Swift /UVOT (Lien et al. GCNC 30600). In the co-added image (10 x 1s exposures) we measure 17.8+/- 0.2 mag. Further analysis is ongoing. The magnitude is calibrated against the USNO-B1 catalog and is not corrected for Galactic extinction in the direction towards the GRB.
  We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for its excellent support.
• GCN Circular #30603
  P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
  Using 1337 s of XRT Photon Counting mode data and 4 UVOT images for GRB 210807A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 76.68376, +58.24980 which is equivalent to:

  RA (J2000): 05h 06m 44.10s
  Dec (J2000): +58d 14' 59.3"
  

  with an uncertainty of 2.1 arcsec (radius, 90% confidence).
  This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
  This circular was automatically generated, and is an official product of the Swift-XRT team.
• GCN Circular #30607
  V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
  R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
  R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
  D. Buckley (South African Astronomical Observatory),
  O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
  A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
  V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
  MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210807A ( A. Y. Lien et al., GCN 30600) errorbox 32639 sec after notice time and 33871 sec after trigger time at 2021-08-07 19:28:12 UT, with upper limit up to 16.6 mag. The observations began at zenith distance = 76 deg. The sun altitude is -21.7 deg.
  The galactic latitude b = 11 deg., longitude l = 152 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1683291
  We obtain a following upper limits.

  Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
  _________|_____________________|_____|_______|______|________
  
     33962 |      MASTER-Tavrida |   C |   180 | 13.4 |        
     35859 |      MASTER-Tavrida |   C |   180 | 16.6 |        
  

  Filter C is a clear (unfiltred) band.
  The observation and reduction will continue. The message may be cited.
• GCN Circular #30616
  V. Kim (FAI, Pulkovo Observatory), A. Pozanenko (IKI), M. Krugov (FAI), N. Pankov (HSE, IKI), S. Belkin (IKI) report on behalf of GRB IKI FuN:
  The name of GRB was indicated incorrectly in GCN Circ. #30614. The observation and photometry in GCN Circ. #30614 indeed refer to the GRB 210807A.
  We apologize for possible inconvenience.
• GCN Circular #30617
  A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU) and A.Y. Lien report on behalf of the Swift-XRT team:
  We have analysed 3.1 ks of XRT data for GRB 210807A (Lien et al. GCN Circ. 30600), from 208 s to 86.2 ks after the BAT trigger. The data comprise 488 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 30603).
  The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=0.71 (+/-0.09). At T+384 s the decay steepens to an alpha of 2.8 (+0.7, -0.6). The light curve breaks again at T+497 s to a decay with alpha=1.02 (+/-0.03), before a final break at T+32.3 ks s after which the decay index is 2.1 (+1.0, -0.7).
  A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.82 (+/-0.03). The best-fitting absorption column is 5.52 (+0.24, -0.23) x 10^21 cm^-2, in excess of the Galactic value of 3.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.71 (+0.15, -0.12) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.6 x 10^-11 (5.9 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Total column:	     3.4 (+0.6, -0.0) x 10^21 cm^-2
  Galactic foreground: 3.4 x 10^21 cm^-2
  Excess significance: <1.6 sigma
  Photon index:	     1.71 (+0.15, -0.12)
  

  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01064221.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #30618
  GRB 210807A: Swift/UVOT Detection
  S. J. LaPorte (PSU) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 210807A 210 s after the BAT trigger (Lien et al., GCN Circ. 30600). A source consistent with the XRT position (Lien et al. GCN Circ. 30600) is detected in the initial UVOT exposures.
  The preliminary UVOT position is:

      RA  (J2000) =  05:06:43.89 =  76.68289 (deg.)
      Dec (J2000) = +58:14:59.2  =  58.24979 (deg.)
  

  with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
  Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

  Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
  
  b                        489            683            38        >17.84
  u                        639            659            19        >17.04
  v                        390            583            39       16.58+-0.25
  uvw1                 440            633             38        >17.12
  uvw2                 539            721             26        >17.08
  white                 234            383           147          16.93+-0.04
  white                 234            708           184          17.19+-0.05
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.409 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #30623
  T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team):
  Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210807A (trigger #1064221) (Lien et al., GCN Circ. 30600). The BAT ground-calculated position is RA, Dec = 76.666, 58.257 deg which is

     RA(J2000)  =  05h 06m 39.7s
     Dec(J2000) = +58d 15' 25.6"
  

  with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 28%.
  The BAT light curve showed a complex structure with a duration of about ~200 sec. T90 (15-350 keV) is 156.30 +- 214.60 sec (estimated error including systematics).
  The time-averaged spectrum from -19.544 to 640.052 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.26 +- 0.08. The fluence in the 15-150 keV band is 9.5 +- 0.4 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+70.52 sec in the 15-150 keV band is 1.8 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
  The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1064221/BA/
• GCN Circular #30624
  J. Ripa (Masaryk U.), M. Ohno (Eotvos U./Hiroshima U.), H. Takahashi (Hiroshima U.), A. Pal, L. Meszaros, B. Csak (Konkoly Observatory), N. Werner, M. Topinka, F. Munz, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Yuusuke Uchida, Helen Poon, H. Matake, N. Uchida (Hiroshima U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.); S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.) -- the GRBAlpha collaboration.
  The long duration GRB 210807A (Swift-BAT detection; Lien et al. GCN Circ. 30600) was detected by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020). This is the first time that a GRB was observed by a 1U CubeSat dedicated to gamma-ray burst observations.
  The data acquisition started at 10:05:14 UT and the tail part of the prompt emission, which consists of multiple peaks, was observed with a duration of about 80 sec. The 7.3 sigma detection significance was confirmed at around 10:06:00 UT.
  The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB210807A.pdf
  GRBAlpha is a demonstration mission for a future CubeSats constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. GRBAlpha was launched on 2021 March 22 from Baikonur. After its commissioning phase, the scientific observations are now under way. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.
• GCN Circular #30628
  S. Schmidl, A. Nicuesa Guelbenzu, S. Klose, S. Melnikov, B. Stecklum, U. Laux (all Tautenburg) and J. Greiner (MPE Garching) report:
  We observed the field of GRB 210807A (Lien et al., GCN 30600) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD camera.
  Observations started at 23:19 UT on August 7, about 13 hours after the GRB trigger. For the optical afterglow (Lien et al., GCN 30600; Hu et al., GCN 30602; LaPorte et al. GCN 30618) we measure the following magnitudes:

  r = 21.66 +/- 0.18, at a midtime of August 7, 23:28 UT,
  i = 21.25 +/- 0.19, at a midtime of August 8, 01:16 UT,
  z = 20.52 +/- 0.19, at a midtime of August 8, 01:26 UT.
  

  Second-epoch observations were performed the following night. The optical transient was not detected anymore:

  r  22.2, at a midtime of August 8, 23:34 UT,
  i  22.4, at a midtime of August 9, 00:38 UT,
  z  21.2, at a midtime of August 9, 01:20 UT.
  

  Given magnitudes are calibrated against the Pan-STARRS catalogue.
• GCN Circular #30637
  S. Belkin (IKI), A. Pozanenko (IKI), V. Kim (FAI, Pulkovo Observatory), R. Ya. Inasaridze (AbAO), E. Klunko (ISTP), M. Krugov (FAI), N. Pankov (HSE), D. Datashvili (AbAO), V. R. Ayvazian (AbAO), G. V. Kapanadze (AbAO) report on behalf of IKI GRB FuN:
  We continued observation of the GRB 210807A (Lien et al., GCN 30600; Ripa et al., GCN 30624) with AZT-20 of Assy observatory, AZT-33IK of Mondy observatory, and AS-32 of Abastumani observatory.
  The optical transient GRB 210807A (Lien et al., GCN 30600; Hu et al., GCN 30602; Lipunov et al., GCN 30607; Kim et al., GCNs 30614, 30616; LaPorte et al., GCN 30618; Schmidl et al., GCN 30628) was detected in almost all of our stacked images. Preliminary photometric results are presented below:

  Date       UT start  t-T0     Filter Exp.   OT    Err.  UL(3sig) Observ.
                        (mid, days)        (s)
  2021-08-07 23:46:09  0.58957   R     53*60  20.94 0.09 21.6    AbAO
  2021-08-09 17:11:54  2.31822   R     30*120 22.6  0.35 22.5    Mondy
  2021-08-10 17:22:17  3.32334   R     27*120 n/d   n/d  22.7    Mondy
  2021-08-10 21:33:07  3.50135   r(AB) 65*60  23.14 0.26 23.7    Assy
  

  The photometry is based on the nearby stars of the USNO-B1.0 catalog.

  USNO-B1.0_id R2
  1482-0188929 16.72
  1482-0188954 15.47
  1482-0189006 15.38
  

  and based on the same stars presented in PS1 catalog for r(AB) calibrations.
  The light curve plotted based on available data for can be found at
  http://grb.rssi.ru/GRB210807A/GRB210807A_LC.png
  The light curve can be approximated by broken power law with power law indices of -0.55 and -1.05 before and after break at about 0.22 days.